Try playing in windowed mode, Suz. When you click on the exe, quickly press Ctrl and the setup menu comes up. Select it from there and it should be fine. I had a quick look and it was a bit jumpy on my machine too, but not too bad.

I agree with Gerty. I never look at walkthroughs all the way through as I am happy getting through a level on my own, but it is nice that they are available just in case I do get stuck. I prefer looking at the stuck threads first, though.